Laparoscopic procedures generally involve excising or manipulating tissue through an opening in the body typically through a cannula through which a pivoting jaw type surgical instrument is inserted. Various mechanisms have heretofore been proposed for actuation of the jaws of such devices. Examples are U.S. Pat. Nos. 2,790,437; 5,171,256; 5,171,258; 5,172,700 and 5,192,298. Typically the instrument, including handle, shaft and working tip are all reusable. However, particularly in the case of scissors, the delicate blades dull or are easily damaged. Thus it is desirable and cost efficient to be able to replace just the working tip components of the instrument.
The prior art instruments have tended to either have one stationary jaw and one pivotal jaw or to use an actuating mechanism, for causing pivoting of both jaws, that has a significant number of working parts. A need has, thus, existed for an instrument wherein a simplified mechanism is provided for causing pivoting of jaws or blades.